Numbers 1:1-3

1The Lord spoke to Moses in the tent of meeting in the Wilderness of Sinai, on the first day of the second month of the second year after Israel’s departure from the land of Egypt:

2“Take a census of the entire Israelite community by their clans and their ancestral families, counting the names of every male one by one.

3You and Aaron are to register those who are twenty years old or more by their military divisions — everyone who can serve in Israel’s army.